Sound Treatment That Revives Hope

Cyberknife Radiosurgery in a case of Bilateral
Acoustic Neuroma

THE CASE

A 43 year old male from Nigeria, a known Hypertensive, was admitted to
BLK Super Speciality Hospital, New Delhi with a history of diminished
hearing from the left ear and gait instability. On evaluation, the MRI
brain revealed extra-axial mass in bilateral cerebello-pontine (CP)
angle with mass effect in left side and upstream ventricular dilatation,
suggestive of Acoustic Neuroma. He underwent decompression surgery
in 2010 in Nigeria. He was advised for Radiosurgery but could not
undergo the same due to logistic reasons. He was well until May 2016
when he suddenly experienced severe headache. The MRI revealed
increase in the size of lesion with hydrocephalus. Subsequently, he
underwent VP shunt placement in June 2016 followed by microsurgery
for the left CP angle tumour in July 2016 elsewhere. After surgery
he developed diminished vision in both the eyes, facial deviation and
incomplete closure of the left eye.

He was brought to BLK in April 2017. On examination, his higher
mental functions were normal with ataxia and left sided facial palsy.
The MR scan showed heterogeneously enhancing mass lesions in the
B / L cerebello-pontine angle cistern extending to the B / L internal
auditory meatus causing indentation of the brain stem, pons and
extending along the dural margin to the premedullary cistern. The
pure tone audiometry showed moderate to severe sensori-neural
hearing loss in left side and moderate sensory neural hearing loss in
the right side.

THE PROCEDURE

He was planned for Cyberknife Radiosurgery for the right CP angle
mass to be followed by interval Cyberknife treatment for the left side
CP angle mass after 6 months. After informed consent, the patient
was taken for treatment planning. An orfi t uniframe was fabricated
for immobilisation and reproducibility. The simulation was carried out
with CT scan and MR Image fusion was done for target and organs at
risk of delineation. A dose of 1650 cGy in 3 fractions was prescribed
at 80% isodose level covering 95% of the target volume (GTV). The
treatment planning was performed on MultiPlan® ver. 4.6 as per the
prescribed dosage and OARs constraints. The dose to 95% of the GTV
was 1651 cGy with conformity index (CI) 1.14 and homogeneity index
1.27. The beams were planned in such a manner that there was no
entry or exit beams from the eyes and the dose fall off to the brain stem
and right cochlea were well below the tolerance limit.

THE RESULT

The patient withstood the treatment very well and there was no acute
treatment related complication. He was sent back to his country on the
next day of the treatment.